Somebody KERS!

February 14th, 2010

Last August, I posed the question, “Who KERS?” in regards to the limited success of the Kinetic Energy Recovery System employed in the 2009 Formula 1 season, and the elimination of the system for 2010.  Well, it turns out that at least one of the systems developed by an F1 team will in fact live on.

As recently described by AutoBlogGreen, Porsche is utilizing the Williams-developed flywheel-based energy storage system in its 911 GT3 R Hybrid.  The 911 GT3 R is the race version of Porsche’s bread-and-butter 911.  The hybrid system leaves the conventional 480-hp flat-6 powering the rear wheels untouched, while adding a pair of 80-hp electric motors to each of the front wheels.

Porsche 911 GT3 R Hybrid

Porsche has always done things a little differently than other automakers, at least with respect to the 911.  Instead of competing in the horsepower wars using 8-, 10- and 12-cylinder engines with massive displacement, they’ve continually developed their horizontally opposed 6-cylinder combined with lightweight (and often exotic) materials to maintain their competitive edge.  Until just over a decade ago, this engine was still air-cooled, in contrast to literally every other automaker’s water-cooled powerplants.  And even now, in a triumph of engineering over physics, Porsche still hangs the motor way out back behind the rear axle.  So it comes as no surprise that they’ve taken the less-traveled path of using a flywheel (instead of a battery) to recovery the energy from braking.

In the simplest terms, the system works by the front-axle motors acting as generators to convert the kinetic energy of the spinning wheels to electrical energy under braking.  The electrical energy is then converted back to kinetic energy at the flywheel (which is essentially another electric motor), as it spins at speeds up to 40,000 rpm.  Under acceleration, the flywheel then acts as a generator, converting the kinetic energy of its spinning mass to electricity, which is routed to the front-wheel motors, where it is converted back to kinetic energy to help power the wheels. (One thing I’ve often wondered in systems like this is – why all the conversions? You want kinetic energy to move the car, and with a flywheel you’ve got a kinetic energy storage system.  Seems like there’d be fewer conversion losses if you could skip the electro-part of the electro-mechanical system, and just connect the flywheel to the drive system by an intelligently activated clutch or viscous coupling.  I’m sure the hybrid system designers out there could give me countless reasons why this wouldn’t work, however.)

And finally, am I a hypocrite because I like this car so much more than the BMW X6 ActiveHybrid, which I criticized here?  Of course not.  BMW has taken a conventional fuel-efficient technology and applied it to a mass-market car solely for performance purposes, with almost no efficiency benefit.  (Plus, the X6 is ugly.)  Porsche, on the other hand, has taken an unproven fuel-efficient technology, and applied it to a limited production race-car as sort of a rolling laboratory to spear-head the development of this new technology, before potentially applying it to its road-going cars.

And although I (like many others) question the feasibility of flywheels as the energy storage solution for mass-market hybrid vehicles, people also once criticized the throwing-a-dart-backwards handling characteristics of the rear-engined 911.  And by most measures, Porsche has been successful with that effort…

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